The underlying hypothesis behind this proposal is that levels of endogenous antibiotics in airway surface liquid are reduced in cystic fibrosis. Accordingly, the specific aim is to obtain nasal secretions from patients with and without CF. Levels of lactoferrin and lysozyme in the secretions will be measured and normalized to volume, protein and mucin content. Serous cells of airway submucosal glands are rich in a variety of natural antibiotics such as lactoferrin and lysozyme. Fluid secretion by serous cells is greatly reduced in CF. It is also possible that altered trafficking of secretory vesicals in cystic fibrosis reduce the amounts of antibiotics reaching the airway surface. This would contribute to the colonization of airways in cystic fibrosis by pseudomonas and other pathogens, which is characteristic of this disease.